解一元二次方程
#include<stdio.h>
#include<stdlib.h>
#include<math.h>

main()
{
    float a,b,c,d,x,x1,x2;

    printf("please input three fioat number");
    scanf("%.4lf%.4lf%.4lf",a,b,c);

    d=b*b-4*a*c;
    if(fabs(a)<1e-6){
        printf("The equation is not quadratic");}
    else if(fabs(d)<=1e-6){
        x=-b/2/a;
        printf("The equation has two equal roots:%.4f %.4f",x,x);}
    else if(d>0){
        x1=(-b+sqrt(d))/2/a;
        x2=(-b-sqrt(d))/2/a;
        printf("The equation has two distinct roots %.4f anf %.4f",x1,x2);}
    else if(d<0){
        x1=-b/2/a;
        x2=-b/2/a;
        x=sqrt(-d);
        printf("The equation has two complex roots %.4f+%.4fi and %.4f+%.4fi",x1,x,x2,x);}

    system("pause");
    return 0;
}
刚学编程，找了好久不知道错误在哪？请各位帮帮忙，谢谢了

谢谢上面的两位姐姐，我发现我好傻啊，呵呵